Device for cutting and gripping threads in circular knitting machines and the like

ABSTRACT

This disclosure relates to a device for cutting and gripping threads in circular knitting machines of the type with a fixed needle cylinder and a fixed needle dial arranged thereon and rotating thread guide units, said device comprising a shears unit including a cam-actuated mobile blade which extends radially to said needle dial and a counterblade which extends tangentially to the needle dial; resilient means being provided for permitting slight adaption movements of said counterblade tangentially to said needle dial.

United States Patent Piana et al.

[ 51 Feb. 8, 1972 [54] DEVICE FOR CUTTING AND GRIPPING THREADS IN CIRCULAR KNITTING MACHINES AND THE LIKE [72] Inventors: Francesco Piana; Angelo Brega, both of Varese, Italy [73] Assignee: Mecmor S.p.A., Milan, Italy [22] Filed: May 6, 1969 [2]] Appl. No.: 822,149

[30] Foreign Application Priority Data May 6,1968 Italy; ..16151 M68 [52] US. Cl. ....66/19, 66/142, 66/145 R [51] Int. Cl. ..D04b 9/06 [58] Field oiSearch ..66/145, 145 8,142,19

[56] References Cited UNITED STATES PATENTS 7/1970 Tannert; .66/19 357,816 2/1887 Chawner ..66/145 1,356,060 l0/1920 Fisher..... 3,081,609 3/1963 Mahler ..66/ 145 UX FOREIGN PATENTS OR APPLICATIONS 660,306 2/1964 Italy ..66/145 Primary Examiner-Robert R. Mackey AttorneyGuido Modiano and Albert Josif [57] ABSTRACT This disclosure relates to a device for cutting and gripping threads in circular knitting machines of the type with a fixed needle cylinder and a fixed needle dial arranged thereon and rotating thread guide units, said device comprising a shears unit including a cam-actuated mobile blade which extends radially to said needle dial and a counterblade which extends tangentially to the needle dial; resilient means being provided for permitting slight adaption movements of said counterblade tangentially to said needle dial.

2 Claims, 7 Drawing Figures PMENTEBFEB amz 3540.094

sum 2 or 2 INVENT FRANCESCO NA ANGELO BREGA AGENT DEVICE FOR CUTTING AND GIPING ADS IN cmcnmn KNITTING MAC AND Tim HIKE BACKGROUND OF THE INVENTION The present invention relates to a device for cutting and gripping threads in circular knitting machines and the like.

From the British Pat. No. 1,000,387, it is known that in circular knitting machines of the type in which the needle cylinder and the needle dial arranged thereon are fixed and the mantles rotate fast with the thread guide units, that is in circular knitting machines which knit open tubular fabric, the problem of cutting the threads with precision at the end of the formation of each row of knitting is of particular importance. That is, it is necessary for the thread which is to be cut, and which proceeds from the thread guide which is rotated about the cylinder and the dial, not to fluctuate due to such movement, but rather be firmly gripped and maintained taut in order to guarantee an efficient cutting action by the shears arranged for such purpose.

The main object of the invention is that of providing a device for cutting and gripping threads in a circular knitting machine of the type mentioned above which permits such operation to be carried out in simple and, at the same time, safe manner.

Another object of the invenfion is that of providing a device for cutting and gripping threads in a circular knitting machine which is controlled by the same members employed for carrying out other operations, namely for the selection of the needles.

SUMMARY OF 'II-IE INVENTION According to the invention there is provided a device for cutting and gripping threads in circular knitting machines and the like of type with a fixed needle cylinder and a fixed needle dial arranged thereon and rotating thread guide units, characterized in that one shears blade for cutting the threads arranged on the needle dial defines on its rear a butt which engages a control cam, and extending radially with respect to the needle dial, cooperates with a platelike counterblade which extends tangentially to the said needle dial and is in engagement with resilient means arranged to permit a certain adaption mobility of said counterblade in a direction tangential to the needle dial of the machine.

Advantageously said cutting blade cooperates, and is fast with a thread braking or retarding pincer arranged to grip the thread during the cutting operation.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will appear more clearly from the following detailed description of a preferred embodiment of a device for cutting and gripping threads illustrated by way of example in the accompanying drawings relating to the application of the device to a circular knitting machine for manufacturing open tubular fabric e.g., of the type described in the British Pat. No. 1,000,387; that is a machine in which the tubular fabric is open because the needles do not extend along all the circumference of the needle dial and the needle cylinder: consequently each row of knitting is introduced at one end of the tubular fabric and is interrupted at the opposite end. In such drawings:

FIG. 1 shows, in plan view, a segment of the needle dial in which the device according to the invention acts;

FIG. 2 shows, in exploded view, some details of the main components operating in such device;

FIG. 3 is a section of the device taken along the line III--III of FIG. 1;

FIG. 4 shows a section taken along the line IV-IV of FIG.

FIG. 5 is a section along the line V-V of FIG. I;

FIGS. 6a and 6b show the detail of the coupling between the resilient counterblade and the fixed dial structure, in plan view and in vertical section, respectively.

2 DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to said figures, reference numeral 1 indicates a radially grooved fixed needle dial of the knitting machine arranged over the needle cylinder (not shown). Above the dial there slides a rotating unit 2 to which is secured a control cam 3 of the mobile blade of the shears as well as the pincers, as will be seen hereinafter.

As stated above, a sector of the dial and the cylinder is not provided with needles. The device illustrated in FIG. I is placed at the end of the zone of the dial provided with needles.

Assuming that the thread guides of the machine rotate anticlockwise (arrow Fll the formation of the fabric, in FIG. 1, takes place below and before the zone illustrated in detail. On the grooved needle dial 1 there is secured a block 7 in which there is formed a seat or guide 8 which extends tangentially to the dial, and which has an open circular cross section. Inside said guide 8 there is inserted a peg member 9 (FIGS. 60 and 6b which has a length such that, in rest, its end 10 is at the level of the rear wall II of the block 7. Reference numeral 12 indicates a counter blade provided with a cutting edge 13 on the side on which the formation of the knitting takes place. The counterblade 112, which is platelike, is longitudinally secured to the peg 10, for example by means of a screw. In such manner the counterblade I2 and the peg 10 are fast with one another and can be displaced tangentially to the needle dial, guided in the guide seat h. Such movements are, however, opposed on the rear by resilient means such as a resilient lamina M which acts as a spring and is secured at 15 t0 the block 7 so that said counterblade 12 pushes against the end 10 of the peg 9. On the opposite side the movement of the counterblade 12 is limited by the presence of the barlike blade proper of the shears 16.

The barlike mobile blade of the shears 16 which is guided in a respective groove 5, 6 arranged on the grooved block 4 and the grooved dial I, respectively, is provided on its back end with a narrowed seat l7 in which there is inserted a plate 18. Said plate I8 is also inserted in a narrowed seat 19 (FIG. I) provided in the control rod or stick 20, and in a narrowed seat 21 provided in a thread-braking pincer 22 whose working will be described hereinafter.

Associated together in such manner the barlike blade 16, the rod 20 and the pincer 22 are fast with one another and can effect a radial stroke under the action of a butt 23 which extends from the rod or stick 20 and which is guided in a shaped seat 24 (FIGS. I and 3) provided in the overhanging rotating cam 3.

The pincer 22 cooperates with a fixed thread-braking or retarding rod 25 and the seat 24 of the cam is shaped so that at the exit of the thread from the knitting, the rod or stick 20, guided by said groove 24, simultaneously causes the backward movement of the mobile blade 16 and the pincer 22 which respectively cooperate with the counterblade l2 and the fixed rod 25.

On the near side of the cutting shears, in the advance direction of the thread, there also operates a unit of pincers 26 which cooperate the springlike member 28 which grip the thread but do not stop it (hereinafter called thread grippers). More precisely three thread-gripping stemlike pincers are provided (but there may be any number) which are generally indicated at 26. Said pincers are guided in respective grooves 5, 6 and are radially mobile due to the engagement of their butts 2'7 inside the groove 24 arranged on the rotating cam 3. Said stemlike pincers 2d cooperate with the thread gripper members 28 (in the illustrated embodiment there are three) which are pivoted at 29 on the block 7 and maintained in the position shown in FIG. 4 by the action of resilient laminas 30. As deducible from FIG. I, said gripper members 2% are arranged between the pincers 26 and are consequently in register with and pressed by means of resilient laminas 30 against the lands or reliefs which separate the grooves 6.

The working of the cutting and gripping device described above is as follows.

When the thread (which moves together with t e respective thread guide in anticlockwise direction) ieaves work zone after it has been knitted both by e needles of the cylinder and the needles of the dial, it arrives adjace the cutting and gripping device. Correspondingly, the profile 24 of the rotating earn 3 reaches the same zone and causes the ward centripetal movement first of the butts 2? and then of the butt 23. This causes first the pincers as to move om the position A to the position B, the transfer of the thread from the position I to the position il under the action of thread g ippers 28; here the thread remains locked together vtridi the former until, pushed by the thread of the next row of the manufactured fabric which is to be cut, it is expelled to the position iii in which the pieces of thread have become selvage; a moment later there takes place the backward movement or" the control rod 20 which, fast with the blade 16 and the thread-braking pincer 22 through the plate 13, causes the backward movement thereof so that the thread while being 5 :ided parallei to the counterblade i2 is braked in its anticlockwise :ovement simultaneously with the cutting action produced by the blade 16. The cutting which is effected on the thread is clear: and precise since there is practically no play between the cutting edge 13 and the shears blade. This lack of play is not harmful since, according to the force which is exercised the cutting edge 13 (and dependent upon vmious factors among which are an imperfect adjustment, or a variable thickness of thread), the counterblade H2 is able to adapt readiiy due to its resilient tangential positioning to the machine.

After the thread has been cut it is released by the threadbraking pincer 22 and carried by its thread guide along the arc of the dial not provided with needles and then engaged by pincer means arranged adjacent the initial working zone of the dial 1 provided with needles for being knitted again by the needles of the dial and the cylinder. Said pincer means may be equal to that indicated with 25, 2%,

Numerous modifications and variations may be made within the scope of the appended claims.

We claim:

1. In a circular knitting machine having a fixed needle cylinder and a fixed needle dial arranged thereon and a rotating unit holding the thread guides for manufacturing open tobular fabric having two selvedges, a device for cutting and gripping threads to form said selvedges, corn ig radiai grooves in "aid needle dial distributed over a sector of said did, stemiilre pincer means for the threads slidably mounted in said grooves, thread-braking means arranged on said needle diai, cutting means having a bariike member slidable in one of sa d grooves and a counterblade member arranged tangentially to said barlike member, resilient means urging said ccunterb de member against said barlike member, cam means provided on the surface of said rotating unit facing said needle dial and control means cooperating with said cam means to con rol said stemlilce pincer means and said cutting and thread-braking means, wherein, according to the improvement, said thread-braking means comprise a first rod member fined in one of said radial grooves and having a hooked end projecting outside said fixed needle dial for engaging the thread and a second rod member arranged slidably in a groove adjacent the groove in which said first rod member is ..ged and having a hooked projecting end and a narrowed seat near the opposite end thereof, wherein said barlike member of said cutting means has a cutting surface at the external end coomrating with said counterblade member and a narrowed seat near the opposite end thereof and wherein said control means cooperating with said cam means to control said cutting and thread-braking means comprise s sticklike m mber slidable inside one of said grooves and having a narrowed scat its internal end and a butt formation cooperating with said cam means, a plate member engaging said narrowed seat of said barlike member, said sticklike member and said second rod member, respectively, thereby to cause rigid simultaneous radial movement of said thread-braking means and said cutting rodlike member in cooperation with 22 control means. I

2. device according to claim 1, wherein said cutting means for cutting the thread to form the selvedges of the open tubular fabric further comprise a blocklike member rigid with said fined needle dial, a guide in said blocklike element extend ng subsuuitialiy in a direction tangential to said fixed needie dial, a peg member slidable inside said guide, said counterblade member mounted on said peg member said resilient means comprising a spring member on said blocklike member urging peg member inside said guide in the direction of said barlilce member or" said cutting means, thereby to approach said counterblade to said barlike member. 

1. In a circular knitting machine having a fixed needle cylinder and a fixed needle dial arranged thereon and a rotating unit holding the thread guides for manufacturing open tubular fabric having two selvedges, a device for cutting and gripping threads to form said selvedges, comprising radial grooves in said needle dial distributed over a sector of said dial, stemlike pincer means for the threads slidably mounted in said grooves, threadbraking means arranged on said needle dial, cutting means having a barlike member slidable in one of said radial grooves and a counterblade member arranged tangentially to said barlike member, resilient means urging said counterblade member against said barlike member, cam means provided on the surface of said rotating unit facing said needle dial and control means cooperating With said cam means to control said stemlike pincer means and said cutting and thread-braking means, wherein, according to the improvement, said thread-braking means comprise a first rod member fixed in one of said radial grooves and having a hooked end projecting outside said fixed needle dial for engaging the thread and a second rod member arranged slidably in a groove adjacent the groove in which said first rod member is arranged and having a hooked projecting end and a narrowed seat near the opposite end thereof, wherein said barlike member of said cutting means has a cutting surface at the external end cooperating with said counterblade member and a narrowed seat near the opposite end thereof and wherein said control means cooperating with said cam means to control said cutting and thread-braking means comprise s sticklike member slidable inside one of said grooves and having a narrowed seat near its internal end and a butt formation cooperating with said cam means, a plate member engaging said narrowed seat of said barlike member, said sticklike member and said second rod member, respectively, thereby to cause rigid simultaneous radial movement of said thread-braking means and said cutting rodlike member in cooperation with said control means.
 2. A device according to claim 1, wherein said cutting means for cutting the thread to form the selvedges of the open tubular fabric further comprise a blocklike member rigid with said fixed needle dial, a guide in said blocklike element extending substantially in a direction tangential to said fixed needle dial, a peg member slidable inside said guide, said counterblade member mounted on said peg member said resilient means comprising a spring member on said blocklike member urging said peg member inside said guide in the direction of said barlike member of said cutting means, thereby to approach said counterblade to said barlike member. 